Hiking in the Grand Canyon can be a perilous pursuit. Photograph by Pete McBride

Three years ago, in the course of thirteen months, the photographer Peter McBride and the writer Kevin Fedarko hiked from one end of the Grand Canyon to the other. They did it in eight sections, mainly so that McBride could shoot in different seasons. In all, it took them seventy-one days to cover two hundred and seventy-seven river miles and some eight hundred shoe-leather miles, through some of the continent’s roughest hiking terrain—“a whole lot of scratching around the rock puzzles in that giant abyss,” as McBride put it recently.

Before they set off, the Grand Canyon had been hiked nose to tail only nine times in recorded history. There is also a handful of obsessives who have chipped away at it, piece by piece, in the course of decades. “Maybe some crazy ancestral Puebloan did the whole thing, but that wouldn’t make logical sense—they wouldn’t have had any reason to,” McBride said.

panoramic view of the confluence of the Colorado and the Little Colorado. Photograph by Pete McBride

McBride, a native Coloradan who shoots for National Geographic, has been documenting the Colorado River for a decade, sometimes from a perch in an ultralight aircraft. Fedarko, who lives in Flagstaff, Arizona, has guided on the river and is the author of “The Emerald Mile,” an account (with many historical tributaries) of a harrowing speed run of the Grand in a dory during the biggest flood in generations. (As it happens, Kenton Grua, the boatman in the book, was also the first person to walk the canyon, in 1976.) McBride and Fedarko have both become persistent, ardent advocates for preserving the place, in all its spellbinding, inhospitable glory, in abidance with Teddy Roosevelt’s famous dictum, issued during his one visit, in 1903: “Leave it as it is. Man cannot improve on it; not a bit.” Still, this was the first time, and surely the last, that either of them had tried to walk it.

On the trek, they each carried packs that averaged about fifty pounds, containing eight days or so of food, as much water as they could hold, and not much in the way of accommodations. They carried a plastic syringe to draw water from potholes in the rock. McBride carried just one camera, one lens, and a solar charger; on cold nights, he kept the batteries warm in his armpit. The temperature ranged from a hundred and twelve degrees Fahrenheit to five degrees. There were hardly any trails, save for those made by game. “Sheep shit was our G.P.S.,” McBride said. They climbed over a hundred thousand vertical feet. “We went through seven pairs of shoes, four ankles”—they each sprained both—“and two girlfriends” (both McBride’s). There were broken fingers, and surgery to remove a cactus spine. McBride, still a bull of a man at forty-seven, lost thirty-five pounds, and, just five days into the first leg, nearly perished of hyponatremia, salt depletion from over-hydration, which is the leading cause of death in Grand Canyon. Once the project was complete, he needed heart surgery.

McBride, whom I’ve known for many years, had invited me to accompany him on a stretch or two. Fortunately, I had ways to say no. When I turned forty, almost a decade ago, I spent more than two weeks floating the Grand on an unguided raft trip with a group of friends. Not unlike many others who’ve been there, I found it to be just about the most spectacular, humbling place I’d ever been; words or pictures can’t convey the scale. I also discovered that the hiking—up drainages and slot canyons, along cliffs and waterfalls—was often more perilous than paddling the rapids. One day, while I was shuffling quickly and dizzily along an exposed ledge, an unseen overhang caught my shoulder and nearly spun me off the edge and into a ravine. Hiking! Who knew?

This month, in advance of the park’s centennial next year, Rizzoli is publishing a book of McBride’s photos, called “The Grand Canyon: Between River and Rim.” Fedarko, in an introduction, calls it a “a visual requiem.” It aims to capture not just the familiar grandeur but also some of the fragile idiosyncrasies of the between-lands, as an argument for leaving them alone.

“There’s been a thousand books of the Grand Canyon made with pretty pictures,” McBride said. “Our goal was to show how the place is changing. And our trip was more about immersion in the place than an A-to-B, let’s-go-conquer-it glory hunt. People tend to visit the rim or the river but rarely spend much time in between.”

One photograph, which achieved some Instagram renown, in 2016, captures a sense of a canyon at risk. Against a backdrop of cliff and sky, some hundred and fifty helicopters and several dozen motorboats clog a couple hundred yards of canyon—it’s gridlock in “Heli Alley.” The shot is unambiguously a Photoshop merge, a composite of hours of sightseeing traffic (for this reason, National Geographic declined to publish it, when it ran their story about the trip, but it’s still astonishing, even appalling, to gaze upon this aggregation of noise and exhaust)…